I was insured with my previous employer under a group plan (with United Healthcare). I resigned and started my own business. I then switched to Cobra for 18 months. When Cobra expired, I got an individual health insurance immediately from Golden Rule (a subsidiary of United Healthcare). However, Golden Rule had a rider on my plan on a medical condition that was diagnosed when I was insured under Cobra. Could they legally do that? How could (or could I) get an insurance that does not have any rider? As I mentioned, I was continuously insured with the same parent company.

This is one to ask your state's insurance department, but as I understand it, in general if you buy an individual policy from a carrier (vs. join a new group plan) that individual company need not take all comers and can exclude conditions. I suggest you ask your state insurance department